Which condition can result in involuntary movements as a side effect of treatment?

Tardive dyskinesia is a condition characterized by involuntary movements that can occur as a side effect of long-term treatment with certain psychiatric medications, particularly antipsychotics. This dysfunction affects the muscles, leading to repetitive, involuntary movements such as grimacing, lip smacking, and abnormal limb movements. It stems from the way these medications alter neurotransmitter levels in the brain, especially dopamine, which plays a crucial role in motor control.

In contrast, while epilepsy can involve involuntary movements during seizures, it is not a direct result of treatment but rather a symptom of the condition itself. Attention deficit hyperactivity disorder (ADHD) treatments do not typically lead to involuntary movements as side effects, focusing instead on enhancing attention and reducing hyperactive behavior. Myasthenia gravis, which affects the communication between nerves and muscles, also does not generally result in involuntary movements due to treatment but rather manages muscle weakness.

Thus, tardive dyskinesia distinctly stands out as the condition linked to involuntary movements specifically as a consequence of medical treatment, making it the correct answer.